D-Link DSN-5210-10 - xStack Storage Area Network Array Hard Drive Hardware Reference Manual page 10

 A 115.2 Kbps RS-232-C stereo mini-jack diagnostic port for troubleshooting purposes
Complete configuration and management of the storage system are available through the
intuitive, graphical-based xStack Storage Management Center software.
2 Chapter 1 Introduction
For the latest information about supported drives, consult the
Interoperability Matrix found on the D-Link Support Web site:
www.dlink.com